A terminal assembly of this type, which is to be attached to a housing of an electrical device, establishes an electrical connection between the interior of the electrical device and the periphery. In particular sensors, actuators and also a device power supply, which is embodied for instance as a switching device, can be connected in this way.
There are two basic types of terminal. One basic type is the screw-type terminal, in which an electrical line to be connected is introduced by hand into the terminal point, held there and a terminal screw is tightened with another hand. The other basic type of terminal is the tension spring terminal, in which a tool, for instance a screwdriver, is pushed into an unlocking opening with the one hand, in order with the other hand to introduce an electrical line to be attached into the thus unlocked terminal point and to hold it there until the terminal point has deployed its spring terminal effect after removal of the tool from the unlocking opening. With both types of basic terminal, the consecutive working steps “assembling” and “fixing” are therefore always required.
A large number of terminal points is often required, so that they cannot all be to arranged adjacent to one another in the direction of a terminal or housing width. There are therefore multistory terminal units having several terminal series arranged above and at least partially also behind one another in the manner of steps. With such multi-storey terminal units, the space requirement in terms of both the housing exterior and also the housing interior is relatively high. There is thus less space available for other function elements within the housing of the electrical device, such as for instance in accordance with assembled printed circuit boards.
Power switches used in domestic and industrial installations are normally equipped with outlet and feed terminals, which are arranged in terminal receptacles embodied for this purpose on both sides of the housing. The outlet and feed terminals are connected electrically to the assigned terminal paths of the power switch. The electrical connection between an external circuit to be protected and the outlet terminals or the connection between the feed network and the feed terminals is made by terminal screws which are arranged in the upper part of the said terminal. These screws generally comprise an end group, which serves to guide the screw against the conductor of the relevant circuit when the screw is tightened, so that this conductor is rigidly clamped between the screw and the associated terminal lug.
Demands are placed on certain elements in the power switch such that these have a one inch air gap and a two inch creepage distance on the entry side. In screw-type devices, this was previously realized by an additional terminal, like for instance an E-type terminal. For power switches based on tension spring, there was previously no simple and economical solution.